Ultrasonic inspection method for welds

JP7629334B2Active Publication Date: 2025-02-13HITACHI LTD

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Patent Information

Application Number: JP2021070933
Authority / Receiving Office: JP · JP
Patent Type: Patents
Current Assignee / Owner
Filing Date: 2021-04-20
Publication Date: 2025-02-13
Estimated Expiration: 2041-04-20

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【0013】 本発明によれば、マスターデータを準備する必要がなく、しかも未溶着部の未溶着長さを高い精度で測定することができる。

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Abstract

To provide an ultrasonic inspection method for a welded part with which a non-welded length of a non-welded part can be measured with high accuracy.SOLUTION: An ultrasonic inspection method for a welded part includes: for a weld metal part and a non-welded part, on the basis of an oblique angle flaw detection method, making an ultrasonic wave incident from a first incident position of a first ultrasonic probe at a first refraction angle; making an ultrasonic wave incident from a second incident position of a second ultrasonic probe different from the first incident position at a second refraction angle different from the first refraction angle; and measuring a non-welded length of the non-welded part from a first reflected wave based on the first ultrasonic probe and a second reflected wave based on the second ultrasonic probe.SELECTED DRAWING: Figure 7

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Description

[Technical field]

[0001] The present invention relates to an ultrasonic inspection method for inspecting a welded portion by using ultrasonic waves, and more particularly to an ultrasonic inspection method capable of measuring an unwelded length. [Background technology]

[0002] In general, ultrasonic testing is widely used in various industrial fields as a non-destructive testing method for detecting internal defects in objects. Defect detection by ultrasonic testing is carried out by utilizing the phenomenon in which ultrasonic waves are reflected by defects.

[0003] Defect detection using ultrasonic testing involves placing an ultrasonic probe that transmits and receives ultrasonic waves on the surface of the object being inspected, transmitting ultrasonic pulses from the ultrasonic probe, receiving the reflected waves (also called reflected echoes) with the ultrasonic probe, and processing the received reflected waves to determine whether or not there are defects inside the object being inspected.

[0004] By the way, there are two types of welding for welded structures: "full penetration welding," in which the metal completely penetrates the base material in the thickness direction, and "partial penetration welding," in which the metal penetrates only partway through. In the case of "partial penetration welding," unwelded parts remain. In the case of structures in which stress is applied to the welded parts, the static strength and fatigue strength change depending on the unwelded length of the unwelded parts relative to the base material.

[0005] For this reason, there is a demand for checking the unwelded length after welding. As a method for measuring the unwelded length by ultrasonic flaw detection, for example, a technique described in JP-A-2004-333387 (Patent Document 1) (hereinafter referred to as the prior art) is known.

[0006] The prior art described in Patent Document 1 introduces ultrasonic waves into a slit, which is a remaining welded portion in a weld. As a means of determining the quality of the welded state from the reflected waves from the slit, data is created in advance from an artificial defect test piece that is the same as the actual product, and based on this data, the optimum inspection position of the ultrasonic probe for determining the slit height is determined and measured, thereby obtaining highly accurate measured values.

[0007] As a specific means for this purpose, multiple artificially defective test specimens with slits of different heights are fabricated in advance, and multiple echo heights are measured for each of these test specimens when an ultrasonic probe is moved from a specific position toward, away from, and moved from the slit.The measurement results of the echo heights at multiple positions for each of these test specimens are then converted into data, and based on the standard data for test specimens with slits at a height that is the standard for determining whether a weld is good or bad, the measurement position of the probe is determined at a portion where a difference between the data values from other test specimens and the standard data values is clearly apparent.

[0008] Furthermore, master data is created by extracting the echo height of each test piece at this measurement position, and then the echo height of the slit portion at the probe measurement position is measured for the welded portion of the actual product to be inspected, and the measured echo height value of this actual product is compared with the master data to judge the quality of the welding condition. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2004-333387 A Summary of the Invention [Problem to be solved by the invention]

[0010] However, the conventional technology described in Patent Document 1 requires the preparation of a test specimen in advance to obtain master data for comparison. In addition, although the quality of the welded condition can be determined, the unwelded length cannot be calculated, which makes the technology difficult to use.

[0011] An object of the present invention is to provide an ultrasonic inspection method for welded parts that does not require preparation of master data and that is capable of measuring the unwelded length of an unwelded part with high accuracy. [Means for solving the problem]

[0012] In order to solve the above problem, the present invention is characterized in that ultrasonic waves are incident obliquely at a first refraction angle from a first incident position of a first ultrasonic probe to a welded metal portion and an unwelded portion in the same position, and ultrasonic waves are incident obliquely at a second refraction angle different from the first incident position of a second ultrasonic probe, the second incident position being different from the first incident position, and the unwelded length of the unwelded portion is measured from the first reflected wave based on the first ultrasonic probe and the second reflected wave based on the second ultrasonic probe. Effect of the Invention

[0013] According to the present invention, there is no need to prepare master data, and the unwelded length of an unwelded portion can be measured with high accuracy. [Brief description of the drawings]

[0014] [Figure 1] 1 is a configuration diagram showing a configuration of an ultrasonic flaw detection device according to the present invention. [Diagram 2] FIG. 4 is a flowchart showing a procedure for setting inspection conditions in the present invention. [Diagram 3] FIG. 1 is a cross-sectional view showing a cross section of a welded structure having an unwelded portion when no welding deformation occurs according to the design. [Figure 4] FIG. 1 is a cross-sectional view showing a cross section of a welded structure having an unwelded portion in which actual welding deformation has occurred. [Diagram 5]4 is an explanatory diagram showing an ultrasonic wave path in an unwelded portion where no welding deformation shown in FIG. 3 occurs. FIG. [Figure 6] 5 is an explanatory diagram showing an ultrasonic wave path in an unwelded portion where the welding deformation shown in FIG. 4 occurs. FIG. [Figure 7] 1 is a top view showing an arrangement of a welded structure and two ultrasonic probes according to a first embodiment of the present invention. [Figure 8] 8 is an explanatory diagram illustrating an ultrasonic path of the first ultrasonic probe shown in FIG. 7. [Figure 9] 8 is an explanatory diagram illustrating an ultrasonic path of the second ultrasonic probe shown in FIG. 7. [Figure 10] 8 is an explanatory diagram showing an example of a setting screen for setting inspection conditions for the first ultrasonic probe shown in FIG. 7; FIG. [Figure 11] 8 is an explanatory diagram showing an example of a setting screen for setting inspection conditions for the second ultrasonic probe shown in FIG. 7. FIG. [Figure 12] 8 is an explanatory diagram showing an example of a setting screen for setting common inspection conditions for the first ultrasonic probe and the second ultrasonic probe shown in FIG. 7; FIG. [Figure 13] FIG. 11 is a flow chart showing a procedure for measuring the unwelded length. [Figure 14] 8 is an explanatory diagram showing an example of flaw detection images of the first ultrasonic probe and the second ultrasonic probe shown in FIG. 7, and a measurement screen for measuring the unwelded length using these images. FIG. [Figure 15] FIG. 11 is an explanatory diagram showing a welded structure according to a second embodiment of the present invention, the arrangement of an ultrasonic probe in this example, and an ultrasonic path. [Figure 16] FIG. 11 is an explanatory diagram showing a welded structure according to a third embodiment of the present invention, the arrangement of an ultrasonic probe in this example, and an ultrasonic path. [Figure 17] 17 is a configuration diagram showing a positioning jig for the ultrasonic probe shown in FIG. 16. [Figure 18] FIG. 11 is an explanatory diagram showing a welded structure according to a fourth embodiment of the present invention and the arrangement of ultrasonic probes in this example. [Figure 19] 19 is an explanatory diagram that illustrates the arrangement of the ultrasonic probes and the ultrasonic paths illustrated in FIG. 18. FIG. [Figure 20] FIG. 11 is an explanatory diagram showing a welded structure according to a fifth embodiment of the present invention and the arrangement of an ultrasonic probe in this example. [Figure 21] 21 is an explanatory diagram that illustrates the arrangement of the ultrasonic probes and the ultrasonic paths illustrated in FIG. 20. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope. EXAMPLES

[0016] An ultrasonic inspection method for a welded portion according to a first embodiment of the present invention will be described in detail with reference to FIGS.

[0017] The overall configuration of an ultrasonic flaw detector according to a first embodiment of the present invention is shown in Fig. 1. As shown in the figure, the ultrasonic flaw detector is composed of an array-type ultrasonic probe 10 that irradiates ultrasonic waves to an inspection object Smp, an ultrasonic flaw detection control unit 11, and a display unit 12 having a function of displaying a flaw detection image and a function of setting flaw detection conditions.

[0018] The ultrasonic flaw detection control unit 11 is composed of a calculation unit 13 that has the function of setting the phase and intensity of the incident wave from the ultrasonic probe 10, and the function of detecting unwelded parts from the intensity and propagation time of the reflected wave from the ultrasonic probe 10, a delay time control unit 14 that controls the delay time of the incident wave from the calculation unit 13, a pulser 15 for generating an incident wave based on a control signal from the delay time control unit 14, a receiver 16 that receives the reflected wave from the ultrasonic probe 10, and a data collection unit 17 that collects and stores the intensity, propagation time, etc. based on the reflected wave from the receiver 16.

[0019] The array type ultrasonic probe 10 is basically composed of a plurality of piezoelectric vibration elements that generate ultrasonic waves and receive ultrasonic waves returned from the inspection object Smp, and is installed on the inspection surface of the inspection object Smp. Then, ultrasonic waves (incident waves) are generated by a drive signal supplied from the ultrasonic inspection control unit 11, and the reflected waves that appear as the waves propagate through the inspection object Smp are detected, and the reflected waves are input to the ultrasonic inspection control unit 11.

[0020] The ultrasonic flaw detection control unit 11 causes the ultrasonic probe 10 to transmit (incident wave) and receive (reflected wave) ultrasonic waves, and for this purpose, includes the above-mentioned calculation unit 13, delay time control unit 14, pulser 15, receiver 16, and data collection unit 17. The pulser 15 supplies a drive signal to the ultrasonic probe 10, and the ultrasonic probe 10 receives the reflected wave generated by this and sends it to the receiver 16.

[0021] At this time, the calculation unit 13 controls the delay time control unit 14, the pulser 15, the receiver 16, and the data collection unit 17 to drive them so as to obtain the required operation. First, it controls both the timing of the drive signal output from the delay time control unit 14 and the pulser 15 and the input timing of the reception signal by the receiver 16, thereby making the ultrasonic probe 10 function so as to obtain the operation of the phased array method.

[0022] The phased array operation of the array-type ultrasonic probe 10 refers to the operation of controlling the focal depth and incident angle (refractive angle) of the ultrasonic waves to transmit incident waves and receive reflected waves, thereby supplying reflected wave signals from the receiver 16 to the data collection unit 17.

[0023] The data collection unit 17 processes the signals of the reflected waves supplied thereto, and stores them as data necessary for calculation in the calculation unit 13. The calculation unit 13 synthesizes the waveforms obtained by the ultrasonic probe 10 in accordance with the delay time, images the waveforms for each ultrasonic incident angle, supplies them to the display unit 12, and executes an operation of displaying them as a flaw detection image.

[0024] Next, the setting of conditions for measuring the unwelded length by ultrasonic flaw detection will be described with reference to Fig. 2 and Fig. 10 to Fig. 12. Fig. 10 to Fig. 12 show setting screens corresponding to the condition setting steps shown below.

[0025] First, the frequency, element size, element pitch, number of elements, and further the refraction angle (detection range), focal length, number of simultaneous excitations, sound speed required for coordinate calculation, etc. of the ultrasonic probe to be used are determined in advance using design information, etc. Then, based on this, the settings shown in Fig. 10 to Fig. 12 are executed on the screen of the display unit 12 in accordance with the conditions determined in the detection condition setting block 20 of the ultrasonic flaw detector shown in Fig. 2. Note that, in this embodiment, since two ultrasonic probes are used, two "setting tags" (condition setting 1, condition setting 2) are provided in Fig. 10 and Fig. 11.

[0026] As shown in condition setting tags 1 and 2 in Fig. 2 and Figs. 10 to 11, in step S20, a probe to be used for flaw detection is selected. In step S21, the material constant (sound speed) of the inspection object is set. In step S22, the number of elements to be excited simultaneously in the array type ultrasonic probe 10 is set. In step S23, the flaw detection range, i.e., the maximum and minimum values of the refraction angle (or linear scanning range), is set. Also, the fineness (pitch) of the flaw detection is set. In step S24, the focal depth of the ultrasonic waves (flaw detection distance) is set. In step S25, the ultrasonic capture path length is set.

[0027] As shown in the "setting tag" (condition setting 3) in Figs. 2 and 12, in step S26, the pulse voltage related to the strength of the ultrasonic waves is set. In step S27, the pulse width related to the frequency of the ultrasonic waves is set. In step S28, the number of bursts related to the number of times ultrasonic waves are generated is set. In step S29, the base gain, preamplifier gain, and digital gain of the ultrasonic sensitivity (gain) are set. Also, the display mode, etc. are set.

[0028] Next, we will explain the issues with "partial penetration welding." Cross sections of welded structures are shown in Figures 3 and 4. Figure 3 shows a cross section of a welded structure with an unwelded part where no welding deformation occurs in the design, and Figure 4 shows a cross section of a welded structure with an unwelded part where actual welding deformation occurs.

[0029] In this example, as shown in Fig. 3, base material A21 (cylinder) and base material B22 (cylinder) are welded in the shape of a "R-groove." At this time, the weld metal 23 does not reach the back side (inner circumference side) of base material B22, and the design allows for an unwelded portion (also called a notch) 24. However, in reality, as shown in Fig. 4, base material B22 shrinks due to thermal contraction and deforms by pushing base material A21 inward, causing the shape of unwelded portion 24 to change from the designed shape.

[0030] 5, a case will be considered in which an array-type ultrasonic probe 25 is arranged on the surface of the base material B 22 and the unwelded portion 24 is detected by sector scanning. Note that this case is targeted at the configuration in FIG. 3, and is a design configuration.

[0031] The ultrasonic wave path 100 reaches the unwelded boundary portion 24a (the boundary between the weld metal 23 and the unwelded portion 24), and is further reflected and returns to the ultrasonic probe 25. Similarly, the ultrasonic wave path 101 reaches the unwelded end portion 24c (the end portion on the inner periphery side of the unwelded portion 24), and is reflected and returns to the ultrasonic probe 25.

[0032] On the other hand, ultrasonic wave path 102 reaches unwelded intermediate portion 24b (partway through unwelded portion 24), is reflected, and does not return to ultrasonic probe 25. As a result, both ends of unwelded portion 24 can be grasped, and the unwelded length can be obtained.

[0033] However, as described above, in reality, the base material B22 shrinks due to thermal contraction during welding, and pushes in and deforms the base material A21, as shown in Figure 6. As a result, a phenomenon occurs in which the propagation path of the ultrasonic waves changes.

[0034] For example, ultrasonic path 103 reaches unwelded boundary 24a, is further reflected, and returns to ultrasonic probe 25. Similarly, ultrasonic path 104 reaches unwelded end 24c, is reflected, and returns to ultrasonic probe 25. Furthermore, ultrasonic path 105 reaches unwelded intermediate portion 24b and is reflected, but since the shape (angle) of unwelded portion 24 has changed from the design shape, it may return to ultrasonic probe 25. As a result, it becomes impossible to grasp both ends of unwelded portion 24, and the unwelded length cannot be obtained.

[0035] Therefore, in this embodiment, as shown in Figures 7 to 9, a method is proposed in which ultrasonic waves are incident on a welded metal portion 23 and an unwelded portion 24 in the same position from multiple incident positions (different positions) and multiple refraction angles (different angles) based on the angle beam inspection method, and reflected waves are detected for each incident position and refraction angle.

[0036] More specifically, this embodiment is characterized in that ultrasonic waves are incident obliquely on the weld metal 23 and the unwelded portion 24 at the same position from a first incident position of a first ultrasonic probe 25a at a first refraction angle, and ultrasonic waves are incident obliquely on a second incident position different from the first incident position of a second ultrasonic probe 25b at a second refraction angle different from the first refraction angle, and the unwelded length of the unwelded portion is measured from the first reflected wave based on the first ultrasonic probe and the second reflected wave based on the second ultrasonic probe.

[0037] 7, a first ultrasonic probe 25a is disposed at a position farther from the weld metal 23 in the direction of the axis (C) of the base metal B22, and a second ultrasonic probe 25b is disposed at a position closer to the weld metal 23, and ultrasonic inspection is performed on the weld metal part 23 and the unwelded part 24 at the same position. Note that the weld metal part 23 and the unwelded part 24 at the same position are not specific positions, but are a concept of an area (the same area) having a spread that is subjected to ultrasonic inspection.

[0038] Moreover, the first ultrasonic probe 25a and the second ultrasonic probe 25b are configured as separate probes and housed in one housing, and can be handled as an integrated ultrasonic probe 25.

[0039] The first ultrasonic probe 25a and the second ultrasonic probe 25b are arranged side by side along the axis (C), and each of the ultrasonic probes 25a, 25b irradiates ultrasonic waves obliquely toward the weld metal 23. This method of irradiation is well known.

[0040] 8 and 9, the ultrasonic wave incidence position of the first ultrasonic probe 25a is set to a position farther from the weld metal 23 than the ultrasonic wave incidence position of the second ultrasonic probe 25b, and the refraction angle (θa) of the ultrasonic wave of the first ultrasonic probe 25a is set to a larger angle than the refraction angle (θb) of the ultrasonic wave of the second ultrasonic probe 25b. Note that the refraction angle is a refraction angle known in the field of ultrasonic flaw detection.

[0041] In this way, by always checking whether a reflected wave is detected regardless of the incident position and refraction angle, as described below, it is possible to determine from the two detected reflected waves whether the reflected wave is from the boundary 24a between the welded portion (welded metal 23) and the unwelded portion 24, the end 24c of the unwelded end portion, or the middle portion 24b of the unwelded portion 24. As a result, the unwelded length of the unwelded portion 24 can be accurately measured.

[0042] Specifically, as shown in Fig. 8 (first measurement mode), ultrasonic path 107 from first ultrasonic probe 25a reaches unwelded boundary 24a, is further reflected, and returns to first ultrasonic probe 25a. Similarly, ultrasonic path 108 reaches unwelded end 24c, is reflected, and returns to first ultrasonic probe 25a. Furthermore, ultrasonic path 109 reaches unwelded intermediate portion 24b and is reflected, but since the angle of unwelded portion 24 has changed from the designed shape, it may return to first ultrasonic probe 25a. This is as explained in Fig. 6.

[0043] 9 (second measurement mode), ultrasonic path 110 from second ultrasonic probe 25b reaches unwelded boundary 24a, is further reflected, and returns to ultrasonic probe 25b. Similarly, ultrasonic path 111 reaches unwelded end 24c, is reflected, and returns to second ultrasonic probe 25b. Meanwhile, ultrasonic path 112 reaches unwelded intermediate portion 24b, is reflected at this portion, but does not return to second ultrasonic probe 25b. As a result, both ends of unwelded boundary 24a and unwelded end 24c of unwelded portion 24 can be grasped, and the unwelded length of unwelded portion 24 can be obtained.

[0044] Next, the calculation process of the reflected wave detected by the above-mentioned method will be described. This calculation process of the reflected wave is executed by the calculation unit 13 shown in Fig. 1, but the conditions and instructions for this calculation process can be set on the screen provided in the display unit 12.

[0045] For example, a graphical user interface or the like can be used, which can execute the measurement flow of the unwelded length shown in Fig. 13. Note that this is an example in which two ultrasonic probes 25a and 25b are used, as in the first embodiment.

[0046] First, in step S30, the inspection conditions for the two ultrasonic probes (probe 1 and probe 2) are set. The settings are the same as those shown in the inspection condition setting block 20 in FIG.

[0047] Next, in step S31, two ultrasonic probes are placed on the welded structure to be inspected. The positions of the ultrasonic probes are determined in advance in consideration of design information of the "groove" and the like, so that the areas where the unwelded end 24c and the unwelded boundary 24a shown in Fig. 8 and Fig. 9 exist are included, and the ultrasonic probe 25 is placed at the determined position.

[0048] Next, in step S32, ultrasonic flaw detection is performed by linear scanning. In this ultrasonic flaw detection, the first ultrasonic probe 25a performs flaw detection and collects reflected wave data, and then the second ultrasonic probe 25b performs flaw detection and collects reflected wave data. This allows each reflected wave to be collected individually.

[0049] Next, in step S33, a flaw detection image is obtained based on the reflected waves obtained by the scan. Furthermore, in step S34, the flaw detection images obtained by the first ultrasonic probe 25a and the second ultrasonic probe 25b are compared.

[0050] Next, in step S35, the reflected waves from the unwelded boundary 24a and the unwelded end 24c are extracted, and finally, in step S36, the unwelded length is measured from the coordinates of the extracted reflected waves from the unwelded boundary 24a and the unwelded end 24c.

[0051] An example of a display of a flaw detection image is shown in Fig. 14. A flaw detection image Dpa acquired by the first ultrasonic probe (probe 1) 25a is shown on the left side of the screen, and a flaw detection image Dpb acquired by the second ultrasonic probe (probe 2) 25b is displayed on the right side of the screen. This makes it easy to determine the difference in the reflected waves depending on the flaw detection position.

[0052] If the same frequency is set, the reflected waves of the first ultrasonic probe 25a and the second ultrasonic probe 25b cannot be obtained simultaneously, so the reflected waves of the first ultrasonic probe 25a are obtained first, and then the reflected waves of the first ultrasonic probe 25a are obtained. The data of these reflected waves are stored in the data collecting unit 17 shown in FIG.

[0053] The calculation unit 13 can obtain the unwelded length of the unwelded portion 24 from the data of the reflected waves from the first ultrasonic probe 25a and the data of the reflected waves from the second ultrasonic probe 25b stored in the data collection unit 17.

[0054] In Fig. 14, the flaw detection image Dpa on the left shows the cross-sectional shape of the flaw detection area of the welded structure (as shown in Fig. 3 and Fig. 4, where the deformed part is shown by a dashed line) and the ultrasonic path of the incident wave and the reflected wave, and similarly, the flaw detection image Dpb on the right shows the cross-sectional shape of the flaw detection area of the welded structure and the ultrasonic path of the incident wave and the reflected wave. Note that it is also possible to display the ultrasonic probe as shown by the dashed line if necessary.

[0055] Furthermore, a "scale" showing length is displayed on the X-axis (horizontal axis) and Y-axis (vertical axis) of the display screen. Grid lines 200a, 201a along the Y-axis are displayed on the flaw detection image Dpa so as to overlap with this "scale", and grid lines 200b, 201b along the Y-axis are displayed on the flaw detection image Dpb.

[0056] Furthermore, grid lines 202a, 202b, and 203 aligned along the X-axis are displayed on the flaw detection images Dpa and Dpb. Then, image processing is performed so that echoes of unwelded parts are displayed in the areas where these grid lines intersect.

[0057] 14, echo regions Eha-1 and Eha-2 indicate echo regions from the unwelded boundary 24a. Moreover, echo regions Ehc-1 and Ehc-2 indicate echo regions from the unwelded end 24c. Furthermore, echo region Ehb-1 indicates a reflected wave from the unwelded intermediate portion 24b. However, on the flaw detection screen Dpb, the echo region corresponding to the unwelded intermediate portion 24b does not appear in the flaw detection image acquired by the second ultrasonic probe 25b.

[0058] Then, on the screen, for example, using a mouse pointer Mp, the position of the echo area can be specified by moving each grid line to the echo area. In Fig. 14, grid line 200a indicates the lateral position of the echo area from the unwelded boundary 24a.

[0059] Since both images acquired by ultrasonic probe 25a (probe 1) and ultrasonic probe 25b (probe 2) have respective echo regions Eha-1 and Eha-2, grid line 200b indicating the lateral position of echo region Eha-2 can be made to move in synchronization with grid line 200a.

[0060] Similarly, the mouse pointer Mp is used to identify the echo position from the unwelded end 24c. In Fig. 14, the grid lines 201a indicate an echo region Ehc-1 from the unwelded end 24c in the flaw detection image acquired by the ultrasonic probe 25a (probe 1).

[0061] Moreover, the grid line 201b indicates an echo region Ehc-2 from the unwelded end 24c in the flaw detection image acquired by the ultrasonic probe 25b (probe 2). As described above, the grid line 201a and the grid line 201b can be made to move synchronously.

[0062] Similarly, the vertical positions of the unwelded boundary 24a and the unwelded end 24c are identified by grid lines 202a, 202b, and 203. The coordinates on the screen can be converted to actual distances using the speed of sound, so the unwelded length can be found by this process. The found length can then be displayed on the screen, as shown in FIG. 14. These calculations can be easily performed by the calculation unit 13.

[0063] Furthermore, since the echo area is not a point but has some extent, it is possible to provide a function that automatically moves the grid lines to the peak position of the echo area using an image processing technique such as peak search when the mouse pointer Mp is moved near the echo area.

[0064] In this manner, the present embodiment is characterized in that ultrasonic waves are incident obliquely from a first incident position of a first ultrasonic probe at a first refraction angle to a welded metal portion and an unwelded portion at the same position, and ultrasonic waves are incident obliquely from a second incident position different from the first incident position of a second ultrasonic probe at a second refraction angle different from the first refraction angle, and the unwelded length of the unwelded portion is measured from the first reflected wave based on the first ultrasonic probe and the second reflected wave based on the second ultrasonic probe. This allows the unwelded length of the unwelded portion to be measured with high accuracy. EXAMPLES

[0065] Next, a second embodiment of the present invention will be described with reference to Fig. 15. This second embodiment is characterized in that it uses a large array-type ultrasonic probe 25c, instead of two separate ultrasonic probes 25a and 25b as shown in Fig. 7. The ultrasonic probe 25c is formed by dividing a plurality of ultrasonic transducers into two groups, a first ultrasonic probe 25a and a second ultrasonic probe 25b.

[0066] The array type (Ultrasonic Phased Array) can change the refraction angle and focus of ultrasonic waves by changing the timing (delay time) of transmission from multiple ultrasonic transducers inside. These two probes realize the same operation and function as the above-mentioned two ultrasonic probes 25a and 25b using the ultrasonic flaw detection control unit 11.

[0067] The operation of the ultrasonic probe 25c is the same as that of the first embodiment, and therefore the description thereof will be omitted here. According to this embodiment, it is possible to achieve the effects of facilitating the installation work and the handling. EXAMPLES

[0068] Next, a third embodiment of the present invention will be described with reference to Figures 16 and 17. In this third embodiment, instead of using two separate ultrasonic probes 25a, 25b as shown in Figure 7, as shown in Figure 16, one ultrasonic probe 25a shown by a solid line approaches or moves away from the weld metal 23 at the same position like the ultrasonic probe 25a shown by a dashed line.

[0069] This makes it possible to carry out the first measurement mode by the first ultrasonic probe 25a in FIG. 7 and the second measurement mode by the second ultrasonic probe 25b with a single ultrasonic probe 25a.

[0070] In this way, it is possible to realize the same operation and function as if two ultrasonic probes were used. Note that the operation of this ultrasonic probe 25a is the same as in the first embodiment, so a description thereof will be omitted here.

[0071] Fig. 17 shows a probe positioning jig 31 for moving the ultrasonic probe 25a, and the width (W) is determined to be a width that allows the ultrasonic probe 25a to slide and move. Also, the length (L) is determined to be a length that obtains the arrangement relationship shown in Fig. 7. This allows accurate positioning of the ultrasonic probe 25a before and after its movement. Also, since only one ultrasonic probe 25a is required, it is possible to prevent the cost of the ultrasonic flaw detection device from increasing. EXAMPLES

[0072] Next, a fourth embodiment of the present invention will be described with reference to Figures 18 and 19. In this fourth embodiment, as shown in Figure 7, transmission and reception of ultrasonic waves are not performed by a single ultrasonic probe 25a or ultrasonic probe 25b in common, but as shown in Figures 18 and 19, transmission and reception are performed separately.

[0073] 18, the ultrasonic probe 25at is an ultrasonic probe dedicated to transmission, and the ultrasonic probe 25ar is an ultrasonic probe dedicated to reception. Similarly, the ultrasonic probe 25bt is an ultrasonic probe dedicated to transmission, and the ultrasonic probe 25br is an ultrasonic probe dedicated to reception. Therefore, in operation, the ultrasonic probe 25at and the ultrasonic probe 25ar are paired, and the ultrasonic probe 25bt and the ultrasonic probe 25br are paired.

[0074] The ultrasonic waves transmitted from the ultrasonic probe 25at are reflected and received by the ultrasonic probe 25ar. Similarly, the ultrasonic waves transmitted from the ultrasonic probe 25bt are reflected and received by the ultrasonic probe 25br. The operation of the ultrasonic probe 25d is the same as that of the first embodiment, and therefore the description thereof will be omitted here. This can increase the sensitivity of the ultrasonic probe 25d.

[0075] In addition, the ultrasonic probe 25at and the ultrasonic probe 25ar, and the ultrasonic probe 25bt and the ultrasonic probe 25br are configured as four separate probes and stored in one housing, and can be handled as an integrated ultrasonic probe 25d. EXAMPLES

[0076] Next, a fifth embodiment of the present invention will be described with reference to Fig. 20 and Fig. 21. The fifth embodiment is characterized in that two large array-type ultrasonic probes 25et and 25er are used, instead of four separate ultrasonic probes 25at, 25ar, 25bt, and 25br as shown in Fig. 18. As shown in Fig. 15, the ultrasonic probes 25et and 25er are formed by dividing a plurality of ultrasonic transducers into two groups to form ultrasonic probe 25at and ultrasonic probe 25bt, and similarly, ultrasonic probe 25ar and ultrasonic probe 25br.

[0077] The ultrasonic waves transmitted from the ultrasonic probe 25at are reflected and received by the ultrasonic probe 25ar. Similarly, the ultrasonic waves transmitted from the ultrasonic probe 25bt are reflected and received by the ultrasonic probe 25br. In this embodiment, the operation of the ultrasonic probe 25e is the same as that in the first embodiment, so a description thereof will be omitted here.

[0078] In this embodiment as well, the sensitivity of the ultrasonic probe 25d can be increased, the installation work can be simplified, and the handling can be simplified.

[0079] The present invention is not limited to the above-mentioned embodiments, but includes various modified examples. The above-mentioned embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment. [Explanation of symbols]

[0080] 11...ultrasonic flaw detection device, 12...display unit, 13...calculation unit, 14...delay time control unit, 15...pulsar, 17...receiver, 17...data collection unit, 21...base material A, 22...base material B, 23...weld metal, 24a...unwelded boundary portion, 24b...unwelded intermediate portion, 24c...unwelded end portion, 25...ultrasonic probe, 31...probe positioning jig, 100-112...ultrasonic path.

Claims

1. For weld metal and unwelded parts in the same position of a welded structure, an ultrasonic wave is incident obliquely at a first refraction angle from a first incident position of a first ultrasonic probe, and a first reflected wave is received; an ultrasonic wave is obliquely incident from a second incident position different from the first incident position of a second ultrasonic probe at a second refraction angle different from the first refraction angle, and a second reflected wave is received; A first inspection image based on the first reflected wave of the first ultrasonic probe and a second inspection image based on the second reflected wave of the second ultrasonic probe are compared to extract an unwelded boundary and an unwelded end of the unwelded portion, and an unwelded length of the unwelded portion is measured from the extracted unwelded boundary and unwelded end.